Bug#1106321: iproute2: "ip monitor" fails with current trixie's linux kernel / iproute2 combination

[Yuyang Huang <yuyanghuang@google.com>]

>iproute2 is generally backward compatible with previous kernels yes,

Acked, will submit a patch ASAP.
Could you advise which branch needs the fix?
Is submitting to iproute2-next and iproute2 enough?

Thanks,

Yuyang

On Fri, May 23, 2025 at 10:10 AM Luca Boccassi <bluca@debian.org> wrote:
>
> On Fri, 23 May 2025 at 01:58, Yuyang Huang <yuyanghuang@google.com> wrote:
> >
> > Backward compatibility is broken due to the exit(1) in the following changes.
> >
> > ```
> > + if (lmask & IPMON_LMADDR) {
> > + if ((!preferred_family || preferred_family == AF_INET) &&
> > +     rtnl_add_nl_group(&rth, RTNLGRP_IPV4_MCADDR) < 0) {
> > + fprintf(stderr,
> > + "Failed to add ipv4 mcaddr group to list\n");
> > + exit(1);
> > + }
> > + if ((!preferred_family || preferred_family == AF_INET6) &&
> > +     rtnl_add_nl_group(&rth, RTNLGRP_IPV6_MCADDR) < 0) {
> > + fprintf(stderr,
> > + "Failed to add ipv6 mcaddr group to list\n");
> > + exit(1);
> > + }
> > + }
> > +
> > + if (lmask & IPMON_LACADDR) {
> > + if ((!preferred_family || preferred_family == AF_INET6) &&
> > +     rtnl_add_nl_group(&rth, RTNLGRP_IPV6_ACADDR) < 0) {
> > + fprintf(stderr,
> > + "Failed to add ipv6 acaddr group to list\n");
> > + exit(1);
> > + }
> > + }
> > +
> > ```
> >
> > My patches follow the existing code styles, so I also added exit(1).
> >
> > Link: https://git.kernel.org/pub/scm/network/iproute2/iproute2-next.git/tree/ip/ipmonitor.c#n330
> >
> > I thought iproute2 was intentionally not backward compatible, but it
> > sounds like that's not true.
> >
> > I can submit a fix patch to remove the exit(1), which should fix the
> > backward compatibility issue.
> >
> > Shall we proceed with this proposal?
>
> iproute2 is generally backward compatible with previous kernels yes,
> so it would be great to have a fix for this. Thanks!